The present invention relates to a driving arrangement with a friction clutch for transmission of starting moment and/or braking moment to a shaft to be driven or braked.
Clutch motor drives are known having two clutch disc halves which are in driving connection with a driven shaft and can be coupled by axial displacement alternatively with a driven plate mounted on a continuously rotating motor shaft, or with a braking block. The axial displacement of the clutch disc halves is performed by electromagnets. The driven shaft is rotatably supported in a bearing bracket in which the braking block is also accommodated (as disclosed in the German Pat. No. 1,613,346, the U.S. Pat. No. 3,487,438).
The clutch disc halves may be composed of carrying discs, and friction coatings of elastic material such as cork, mounted on the carrying discs. The friction faces must be such as to withstand, for example in the driving arrangement of the drive of industrial sewing machines, 20000 switching cycles and more per working day. It appears that the friction coating of pressed and grease-treated or oil-treated cork is best suited for such extreme conditions. However, friction faces dry up relatively fast as a result of generated heat and flowing away of the lubricating medium under the action of centrifugal force. This results in squeaking noise.